Fix spec violations in burn_charts_spec
What does this MR do and why?
In regards of epic &5102, this MR fixes the following spec violations in ee/spec/frontend/burndown_chart/components/burn_charts_spec.js
#391066 (closed):
How to set up and validate locally
Run tests:
yarn jest ee/spec/frontend/burndown_chart/components/burn_charts_spec.js
MR acceptance checklist
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I have evaluated the MR acceptance checklist for this MR.
Closes #391066 (closed)